/*
 * Copyright (c) 2004-2022, University of Oslo
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors 
 * may be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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 */
package org.hisp.dhis.webapi.controller;

import io.micrometer.prometheusmetrics.PrometheusMeterRegistry;
import io.prometheus.client.exporter.common.TextFormat;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.UncheckedIOException;
import org.hisp.dhis.common.OpenApi;
import org.springframework.context.annotation.Profile;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

/**
 * @author Luciano Fiandesio
 */
@OpenApi.Document(
    entity = Server.class,
    classifiers = {"team:platform", "purpose:support"})
@Profile("!test")
@Controller
public class PrometheusScrapeEndpointController {
  private final PrometheusMeterRegistry prometheusRegistry;

  public PrometheusScrapeEndpointController(PrometheusMeterRegistry prometheusRegistry) {
    this.prometheusRegistry = prometheusRegistry;
  }

  @GetMapping(value = "/api/metrics", produces = TextFormat.CONTENT_TYPE_004)
  public void scrape(HttpServletResponse response) {
    try {
      response.setContentType(TextFormat.CONTENT_TYPE_004);
      prometheusRegistry.scrape(response.getOutputStream());
    } catch (IOException ex) {
      // This never happens since StringWriter::write() doesn't throw
      // IOException

      throw new UncheckedIOException("Writing metrics failed", ex);
    }
  }
}
